The invention is located in the field of data transfer optical signal regeneration circuits. It is applicable to transmissions the code of which is or is not with return to zero.
The technique is known of using interferometers the arms of which comprise semi-conductor optical amplifiers to make decision windows. These interferometers which use a continuous wave source constituting the output carrier wave may be used in an anti-phase (out of phase) or an in-phase configuration.
When they are used in anti-phase, good non linearity and therefore good reshaping is obtained. However, in this case, the capacity of the converted wave to withstand the signal pulse distortions brought by the line (good chirp qualities) is reduced, when standard fiber is used.
When they are used in phase the capacity of the converted signal to resist signal pulse distortions is improved, but the non linearity is reduced.
An interferometer, the arms of which comprise semi-conductor optical amplifiers, may also be used in conjunction with a recovered clock signal. In this case, in particular when the converter is used in anti-phase, good 3R regeneration is obtained. The capacities of the converted signal to resist line distortions remain good on condition that the clock pulses are of short duration relative to the duration of each of the pulses constituting, together, the signal to be transmitted.
The use of interferometers the arms of which comprise semi-conductor optical amplifiers, whether in phase or in anti-phase, does not make it possible to obtain good decision window characteristics with a single interferometer. The capacities of the signal obtained to resist line distortions are not good enough for direct use as a transmitter.
Multi-stage architectures are therefore inevitable using known technologies. Moreover, these reconstitution solutions are not necessarily the most practical or the most effective for subsequent insertion of timing by introduction of a clock signal.
The version with clock recovery, although superior from the point of view of the decision window and of the capacity to resist pulse distortions, has however, another drawback.
As the clock signal acts directly as a transmission wave, the capacity for resistance to pulse distortions (chirp) may not be satisfactory. It is dependent on the transmission flow rate and on the device used to recover the clock. The transmission wavelength is also fixed by the clock source. Moreover the clock signal may have a low signal to noise ratio.
The present invention is intended to overcome these drawbacks. Its particular aim is to obtain a device capable of 3R regeneration of a signal the flow rate of which may reach 40 gigabits per second and beyond. Another aim is to reconcile a good decision window with low line pulse distortion while reducing the number of requisite components.
To all these ends the aim of the invention is a device for regenerating an input pulse amplitude modulated optical signal, the device comprising an interferometric structure having a first and a second arm, a non linear optical medium being present on each of the arms, input coupling means coupled to said first and second arms, the first arm receiving through these input coupling means the optical signal to be regenerated, output coupling means, coupled to said first and second arms and delivering an interference signal between signals coming from the first and second arms respectively, a device characterised in that the interferometric structure is such that the output is nil when there is no dynamic phase shift between the two arms, and in that the input coupling means couple additionally:
the first and second arms to a continuous optical wave generator;
the second arm to a clock signal generator of the signal to be regenerated
and in that the output of the output coupling means carries the regenerated input optical signal.